2023-04-19 03:14:52

by Haifeng Xu

Subject: [PATCH v2 1/2] memcg, oom: remove unnecessary check in mem_cgroup_oom_synchronize()

mem_cgroup_oom_synchronize() is only used when the memcg oom handling is
handed over to the edge of the #PF path. Since commit 29ef680ae7c2 ("memcg,
oom: move out_of_memory back to the charge path") this is the case only
when the kernel memcg oom killer is disabled (current->memcg_in_oom is
only set if memcg->oom_kill_disable). Therefore a check for
oom_kill_disable in mem_cgroup_oom_synchronize() is not required.

Signed-off-by: Haifeng Xu <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
---
v2: split original into two and improve patch description
---
mm/memcontrol.c | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5abffe6f8389..fbf4d2bb1003 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1999,16 +1999,9 @@ bool mem_cgroup_oom_synchronize(bool handle)
if (locked)
mem_cgroup_oom_notify(memcg);

- if (locked && !memcg->oom_kill_disable) {
- mem_cgroup_unmark_under_oom(memcg);
- finish_wait(&memcg_oom_waitq, &owait.wait);
- mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
- current->memcg_oom_order);
- } else {
- schedule();
- mem_cgroup_unmark_under_oom(memcg);
- finish_wait(&memcg_oom_waitq, &owait.wait);
- }
+ schedule();
+ mem_cgroup_unmark_under_oom(memcg);
+ finish_wait(&memcg_oom_waitq, &owait.wait);

if (locked) {
mem_cgroup_oom_unlock(memcg);
--
2.25.1

2023-04-19 07:52:14

by Michal Hocko

Subject: Re: [PATCH v2 1/2] memcg, oom: remove unnecessary check in mem_cgroup_oom_synchronize()

On Wed 19-04-23 03:07:38, Haifeng Xu wrote:
> mem_cgroup_oom_synchronize() is only used when the memcg oom handling is
> handed over to the edge of the #PF path. Since commit 29ef680ae7c2 ("memcg,
> oom: move out_of_memory back to the charge path") this is the case only
> when the kernel memcg oom killer is disabled (current->memcg_in_oom is
> only set if memcg->oom_kill_disable). Therefore a check for
> oom_kill_disable in mem_cgroup_oom_synchronize() is not required.
>
> Signed-off-by: Haifeng Xu <[email protected]>
> Suggested-by: Michal Hocko <[email protected]>

Acked-by: Michal Hocko <[email protected]>

> ---
> v2: split original into two and improve patch description
> ---
> mm/memcontrol.c | 13 +++----------
> 1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5abffe6f8389..fbf4d2bb1003 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1999,16 +1999,9 @@ bool mem_cgroup_oom_synchronize(bool handle)
> if (locked)
> mem_cgroup_oom_notify(memcg);
>
> - if (locked && !memcg->oom_kill_disable) {
> - mem_cgroup_unmark_under_oom(memcg);
> - finish_wait(&memcg_oom_waitq, &owait.wait);
> - mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
> - current->memcg_oom_order);
> - } else {
> - schedule();
> - mem_cgroup_unmark_under_oom(memcg);
> - finish_wait(&memcg_oom_waitq, &owait.wait);
> - }
> + schedule();
> + mem_cgroup_unmark_under_oom(memcg);
> + finish_wait(&memcg_oom_waitq, &owait.wait);
>
> if (locked) {
> mem_cgroup_oom_unlock(memcg);
> --
> 2.25.1

--
Michal Hocko
SUSE Labs